With the need for better resolution in the lithography used in the manufacture of microcircuits, new processes have been investigated. X-ray lithography, which permits shorter wavelengths to be used, has been proposed as a solution to the resolution problem.
In an x-ray lithography exposure system, the wafer is illuminated by a point source. The flux intensity at the wafer plane varies because of the inverse square law. Because points on the wafer edge are further from the source than points at the center, the flux decreases radially. Flux nonuniformities cause linewidth variations.
Accordingly, it is an object of the present invention to substantially reduce flux variations and the resultant linewidth variations caused by this effect, as will become apparent as the description proceeds.